Loamy 20-40 PZ

Description

The Reference Plant Community of this site is that of an open, mature, ponderosa pine - Douglas-fir stand represented by Community Phase 1.4. This is the most advanced community within the historical disturbance regime for this site, yet occurs across the landscape as a mosaic of plant community phases characterized by variation in community structural stage (tree age, density and cover) and species composition. Historically, Oregon white oak - ponderosa woodlands would have cycled from a shrub bunchgrass young tree stand initiation phase (1.1) to a young woodland phase (1.2) to a mature woodland phase (1.3) with a disturbance regime characterized by frequent, low intensity surface fires with occasional mixed or replacement severity fires (Landfire fire regime group 1). Fire exclusion can lead to closed canopy and dense understory stocking conditions represented by communities 1.2 and 1.5 which can be more vulnerable to stand replacing fires (Devine et al. 2013). Historical evidence suggests that this community type was common across the landscape prior to selective logging and widespread fire suppression, which can alter fire regimes and lead to a greater frequency of high severity fire. Given the likelihood that this state, even in the best condition and highest potential, will almost always include at least some component of exotic species regardless of management inputs, this may also be referred to as the “current potential state”. In this document, the term “reference state” is used synonymously with “current potential state” for the sake of simplicity.

Dominant plant species

1. Douglas-fir (Pseudotsuga menziesii), tree

2. ponderosa pine (Pinus ponderosa), tree

3. Geyer's sedge (Carex geyeri), grass

Submodel

Description

Alterations of forest tree species composition, as well as soil compaction and surface disturbances due to large machine usage may hinder passive forest reestablishment. Ecological forestry practices may promote a return to reference state. Stand replacing fire may lead to a transition to Community 1.1 of the Reference State if soil compaction is not severe, species composition has not been significantly altered and tree seed source is available. Selective removal of large ponderosa pine may advance succession and favor maturation of more shade tolerant trees such as Douglas-fir.

Dominant plant species

1. Douglas-fir (Pseudotsuga menziesii), tree

Submodel